1. Field of the Invention
The present invention relates to a machine for monitoring the vertical position of a contact wire of an overhead line extending above a track comprising two rails having running faces defining a plane, which comprises a self-propelled machine frame including a superstructure, which may be a car box, an undercarriage supporting the machine frame on the track and having wheels journaled on a wheel axle and engaging the running faces of the track rails, and a vertically adjustable measuring yoke mounted on the machine frame.
2. Description of the Prior Art
The maintenance of electric railroad rights of way require not only track work but also the proper maintenance of the overhead line, and this has gained added importance as train speeds have increased, which requires accurate maintenance of the contact wire position. Self-propelled boom cars of the above-indicated type have been used for the maintenance and servicing of overhead lines. Their measuring yoke is a vertically adjustable pantograph mechanism mounted on the car box and, as the car advances along the track, the measuring yoke engages the contact wire and electronically monitors its position, and the monitored data are graphically recorded. While these machines have been successfully used, the vertical measurement results are sometimes falsified because the resilient mounting of the car box on the undercarriage tends to change its distance from the plane defined by the running faces of the track rails.